We plan to study changes in enzyme reactions by histochemical methods in the lens epithelium of rabbits after x-irradiation or mechanical injury. We want to compare changes previously determined in acid phosphatase with two enzymes considered to be lysosomes; Beta glucuronidase and desoxyribonuclease. Specimens (flat lens mounts) will be prepared at intervals from 1 to 112 days after the challenge. Changes in enzyme concentration demonstrated by histochemical reaction will be determined by a densitometer. Other enzymes will also be studied to determine if changes occur similar to those seen in acid phosphatase. Previous studies have indicated malate and lactate dehydrogenases and dehydrogenase co-factor ubiquinone do not show similar changes. This screening project will be done at intervals of 7, 14, and 28 days after challenge. Enzymes to be studied include succinate, glutamate, lipoamide, lactate, malate, isocitrate, glycerophosphate, and glucose-6-phosphate dehydrogenases, gamma-amino- butyric decarboxylase, and cytochrome oxidase.